Let A = {a, b}, B = {a,b, c}. Is A ⊂ What is A U B?

Given the sets A = {1,3,5}, B = {2,4,6} and C = { 0,2,4,6,8}, Which of
the following may be considered as universal set (s) for all the three sets
A,B and C
(i) {0,1,2,3,4,5,6}
(ii)
(iii) {0,1,2,3,4,5,6,7,8,9,10}
(iv) {1,2,3,4,5,6,7,8}

Find the following sets find their union:
(i) A = {a,e,i,o,u}; B = {a,b,c}.
(ii) X = {1,3,5}; Y = {1,2,3}.
(iii) A = {x: x is a natural number and multiple of 3.};
     B = {x : x is a natural number less than 6.}.
(iv) A = {x: x is a natural number and 1 < x < 6.};
       B = {x : x is a natural number and 6 < x < 10.}.
(v) A = {1,2,3}; B = φ.

If A and B are two sets such that A ⊂ then what is A U B?

If A = {1,2,3,4} , B = {3,4,5,6}, C = {5,6,7,8} and D = {7,8,9,10}; find
(i) AB (ii) AC (iii) BC (iv) B D
(v) ABC (vi) ABD (vii) BC D